David Attenborough presents a documentary series exploring how animals meet the challenges of surviving in the most iconic habitats on earth. Remote islands offer sanctuary for some of the planet's strangest and rarest creatures. The rare pygmy three-toed sloth enjoys a peaceful existence on an idyllic Caribbean island, while nesting albatross thrive in predator-free isolation. But island life always comes at a cost. On the Galapagos Islands, young marine iguana must escape an onslaught of deadly racer snakes the moment they hatch from the sand. On the sub-Antarctic island of Zavodovski, life gets more extreme still. Every day, one and a half million penguins risk being battered against the rocks by fierce waves as they try to get on and off the island.